Vehicle Sensor Online Calibration via Dynamic Bias Compensation
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Solution Overview
Problem
Inertial sensors in vehicles, particularly two-wheeled vehicles like electric bicycles, face challenges in calibration due to temperature-dependent and age-related offset errors, which existing offline and online calibration methods struggle to address effectively, especially for accelerometers without gravitational alignment information.
Innovation Solution
A method for online calibration using vehicle-specific movement patterns, including determination of bias-compensated acceleration data during acceleration and deceleration phases, and vehicle speed-based bias determination, allowing for continuous compensation of offsets without the need for offline calibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If offline end-of-line calibration is performed, then manufacturing precision is improved, but device complexity and production time increase
Solution Approach 1:
The patent applies preliminary action by performing calibration during the manufacturing process itself, before the sensor is deployed. The calibration sequence includes determining gravitational acceleration components, calculating rotation matrices, and computing bias values all during production. This eliminates the need for separate offline calibration steps while maintaining manufacturing precision.
Solution Approach 2:
The sensor system performs self-calibration using its own measurements during vehicle operation. The acceleration sensor measures gravitational components and vehicle acceleration, the gyroscope measures rotation rates, and the system integrates these self-generated data to compute and apply bias compensations automatically, eliminating external calibration equipment and procedures.
2Measurement precision
If static calibration methods are used, then measurement precision is improved, but adaptability to different movement states deteriorates
Solution Approach 1:
The patent transitions from static calibration to dynamic calibration by continuously updating bias values during vehicle operation. The system processes acceleration and rotation data in real-time as the vehicle undergoes various movements, enabling the calibration to adapt dynamically to different motion states while maintaining measurement precision through continuous compensation.
Solution Approach 2:
The system changes calibration parameters dynamically based on operating conditions. The bias values are not fixed but are continuously adjusted based on measured gravitational components, vehicle acceleration, and rotation data. This allows the calibration to adapt to varying movement states while maintaining accurate measurements through parameter updates.
3Device complexity
If accelerometer-only calibration is attempted, then device complexity is reduced, but measurement precision deteriorates due to lack of gravitational alignment information
Solution Approach 1:
The patent merges the acceleration sensor and gyroscope into a unified calibration system. The acceleration sensor provides gravitational and linear acceleration data, while the gyroscope provides rotational orientation data. By combining these complementary measurements, the system achieves accurate calibration without requiring separate gravitational alignment equipment, maintaining both low complexity and high precision.
Solution Approach 2:
The gyroscope acts as an intermediary that bridges the acceleration sensor's limitations. While the acceleration sensor measures linear acceleration including gravity, it cannot distinguish orientation changes. The gyroscope measures rotation rates and provides orientation information that mediates the interpretation of acceleration data, enabling precise calibration using only these two sensor types.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach eliminates the necessity for offline calibration, reduces manufacturing costs, and provides continuous compensation for temperature-dependent and age-related biases, offering high flexibility and accurate sensor calibration across various movement states.
Implementation Method 1
Determining first, at least two-dimensional acceleration data from measurements of an acceleration sensor during an acceleration phase of the vehicle
Implementation Method 2
Inertial sensors consist of a gyroscope with three degrees of freedom and an accelerometer
Implementation Method 3
These offsets or biases are temperature-dependent, change over the sensor's lifetime
Data Source
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AI summary
The invention relates to a method for the online calibration of a sensor of a vehicle, in particular a two-wheeled vehicle, comprising the steps of: - determining first, at least two-dimensional acceleration data based on measured values from an acceleration sensor during an acceleration phase of the vehicle, wherein the two-wheeled vehicle is oriented in one spatial direction; - determining second, at least two-dimensional acceleration data during a non-acceleration phase of the vehicle, wherein the two-wheeled vehicle is oriented in the same spatial direction; - determining bias-compensated acceleration data in the plane of the vehicle's longitudinal and vertical axes based on the determined first and second acceleration data; - determining bias data for the sensor in at least one spatial direction, at least based on the vehicle speed; and - calibrating the sensor using the determined bias data and the bias-compensated acceleration data.